Because that was the conditions the guy who ran the test had at his house.
From my original post: “Now, I know: 1 guy, Pats fan, single data point, not the same conditions . . . fine. I am not using this data to prove or disprove what the Patriots did, or did not do, to the game balls, just as a point of interest to this discussion.”
So again, I did not present this data to prove or disprove what did happen during the game. It is a single experiment that shows that footballs that are taken out of room temperature, placed in a colder environment, and then returned to the original room temperature will:
A: show a decrease in PSI after time in the colder environment, and
B: return to approximately the original PSI after 15 minutes in the original temperature
Besides being actual science - something painfully missing from this discussion both on this site and in the media - I believe it explains why the Colts balls had a PSI of 13.5 when measured after the game. Not that their balls maintained a PSI of 13.5 during the entire game, only that the balls had returned to that PSI when measured indoors after the game.
BTW, if you missed my brilliantly presented theory on the last page, the short version is that I believe that the Pats did not deflate the balls after approval by the refs. Rather, they submitted under inflated balls before the game that the refs approved without proper testing. If my theory is true, we will never know what the actual PSI of the Patriots’ balls was pre-game, and thus never know what kind of temperature related PSI decrease, and indoor warming rebound, the half-time measurements actually showed.